1. Field of the Invention
The present invention relates to an illumination apparatus which is used with an image pickup apparatus such as a digital still camera, and particularly relates to an illumination apparatus which is supported so as to surround an outer circumference of an image capturing lens.
2. Description of the Related Art
In micro photography capturing a close distance object, an illumination apparatus with a light emission portion at a tip of an image capturing lens wherein the light emission portion is formed in a ring shape or an arc shape along an outer circumference of the image capturing lens is often used. Japanese Patent Laid-Open No. 2001-215574 discloses an illumination apparatus having a configuration where light sources such as xenon tubes are formed in a circular arc shape and such multiple light sources are arranged along an outer circumference of an image capturing lens to form a ring shaped light emission portion.
The illumination apparatus disclosed in Japanese Patent Laid-Open No. 2001-215574 uses, as the light source, a glass tube, which is manufactured generally as a straight tube such as a xenon tube, formed in an arc shape (curved tubular shape) through a bending process with high accuracy. As a result, there is a problem that a cost to obtain the light source increases and the illumination apparatus becomes expensive. Furthermore, it is difficult to project light emitted from such curved-tubular light sources efficiently and uniformly onto a target object for micro photography. This causes problems that sufficient performance cannot be exhibit in terms of efficiency of light utilization and light distribution.
Moreover, since such illumination apparatuses are portable to be used with cameras (and interchangeable image capturing lenses), it is desirable that they be formed in a small size as much as possible.